The present invention relates to a method for producing a rubber composition that utilizes at least one of oxycellulose fibers and cellulose nanofibers, and a rubber composition that includes at least one of oxycellulose fibers and cellulose nanofibers.
In recent years, cellulose nanofibers obtained by untangling natural cellulose fibers to have a nanosize have attracted attention. Natural cellulose fibers are biomass produced using pulp (wood) as a raw material, and it is expected that environmental burdens can be reduced by effectively utilizing natural cellulose fibers.
For example, a method for producing a rubber composition has been proposed that includes a step that mixes rubber latex with an aqueous dispersion of cellulose fibers, and removes at least part of water from the mixture to obtain a cellulose fiber-rubber composite, and a step that mixes the composite with rubber (see JP-A-2013-18918, for example).
However, since the cellulose fibers form a hydrogen bond, and aggregate during the drying step that removes part of water from the mixture, the aggregates (masses) of the cellulose fibers remain in the rubber composition. Since the aggregates of the cellulose fibers are defects in the rubber composition, the rubber composition cannot be sufficiently reinforced by the cellulose fibers.